1. Field of the Invention
The present invention relates to a touchpad assembly, more particularly to a touchpad construction that has a reduced height.
2. Description of the Related Art
Input devices are required for a computer to allow a user to move a cursor to various locations in a computer display. Many types of user input devices have evolved to allow a user to efficiently operate within a graphical user interface (GUI) environment. Touchpads are among the most popular devices available in the market. With the trend toward minimizing the thickness of notebook computers, the reduction in the height of a touchpad input device is a quite important design consideration for a notebook computer. Moreover, the durability of keys of the touchpad is also an important factor in valuation of the same.
A known structure of a touchpad assembly for a notebook computer is shown in FIGS. 1 and 2. A base member 11 made of plastic material supports a touchpad member 10 thereon and is mounted at a rear part 12 on a portion of the notebook computer. A pair of arms 13 extends forwardly from the rear part 12 of the touchpad member 10, and a keypad 14 extends from the free end of each arm 13. A push bar 15 is provided on the bottom side of the keypad 14, and is used to actuate a corresponding key switch 16 when a pressing force is applied by the user on the respective keypad 14.
The keypad 14 springs back to a normal position when released from the pressing force, owing to the flexibility of the cantilevered arm 13. Because the keypads 14 are frequently pressed during use of the computer, the arms 13 and the keypads 14 must be of considerable thickness in order to provide sufficient durability. The thickness of the arms 13 and the keypads 14 in this conventional construction is generally around 2 mm, which is too thick for application in most laptop computers. Moreover, the frequent operation of the keypad 14 and the arm 13 may eventually result in failure due to material fatigue.
In addition, the touchpad member 10 is often damaged and malfunctions during an electrostatic discharge (ESD) test, where static electricity of several kilovolts is applied by a static generator. For this sake, the touchpad member 10 must be provided with grounding elements in order to dissipate static charge. This leads to a complicated construction and increases the production cost.